1. Field of the Invention
The present invention relates to locks in general, and more particularly to locks that are operated by motors, especially electric motors, and that are well suited for use in motor vehicles to secure such parts as doors, hatches and/or hoods.
2. Description of the Related Art
Motor vehicle locks of the type referred-to above have already been known and used for many years in a variety of constructions and employing a variety of structural and operational principles; a more recent trend is to install such locks in passenger cars not only at the high end of the price spectrum but even in the intermediate range. Electrically powered drives equipped with worm gear transmissions are especially popular choices for this application, the main reason for this preference being their particularly small dimensions. Typically, the output element of such a drive is so connected to the lock catch component that the latter is capable of conducting free movement in the closing sense. This feature is based on the consideration that even a powerful slamming of the car door should result in entrainment of the lock catch component ahead of the drive output element.
Typically, when an auxiliary closing drive that is powered by a motor, especially an electric motor, is employed, it is activated only after the lock catch component has already reached its preliminary closing position. This preliminary closing position is ordinarily that in which the catch component is situated at a preliminary abutment or slightly behind it in the closing direction (overstroke). From there, the catch component is moved by the motor-powered drive in the closing direction, ordinarily one in which the main abutment of the catch component is engaged. The displacement of the lock catch component into its main closing position by means of the corresponding output component of the auxiliary closing drive is, however, often plagued by the problem that, should the output element of the drive come to a stop before the corresponding force-transmitting surface of the lock catch component had been reached, the motor vehicle door may become blocked. Moreover, even during the closing operation itself, that is in the course of closing the vehicle door by means of the auxiliary closing drive, there may arise emergency situations; for instance, adornment chain links or garment pieces may become caught between the door and the door frame. To address this issue, it has already been proposed to employ, as revealed for instance in the European patent document EP-B-0 496 736, mechanical, keyactivated emergency release elements, or coupling linkages or levers that are liftable manually, for instance via the external door handle, as disclosed for example in the German patent document DE-A-38 36 771.
In a known lock for automobile doors or the like (that disclosed in the German patent document DE-A-197 14 992) of which the present invention is a further development, there is provided an uncoupling possibility for the auxiliary closing drive in emergency situations that operates without the need for applying mechanical action or influence from the outside on the lock mechanism. To this end, an electromagnetic coupling is integrated into the step-down transmission embodied in the vehicular door lock of this type, this coupling serving to couple the electrical driving motor with or uncouple it from the driving element. In this construction, the engaged electromagnetic coupling is disengageable even while the electric driving motor is running, in dependence on the satisfaction of an uncoupling criterion. A preferred criterion is the pulling on the external (or the internal) door handle; this starts an electrically executed or performed switching process that leads to or results in the disengagement of the electromagnetic coupling. This corresponds on purpose to the intuitive action taken by the affected person even in the context of a motor vehicle equipped with purely mechanical vehicle door locks when confronted with the need for quickly opening the car door again while the door closing process is already on its way or had even been completed, for instance to release a coat portion clamped between the door and the vehicle body.
In the just referred-to patent document, it is further explained that one could also use, as alternatives to the above solution, a switching off of the drive motor or reversal in the sense of rotation of the electric drive motor of the auxiliary closing drive, on the basis of the release triggering criterion or event.
With respect to further previously proposed technical solutions relevant to this theme, and also to examples of auxiliary closing drives corresponding thereto, attention may and hereby is directed to the aforementioned German patent document DE-A-197 14 992.
The lock for doors or vehicles or the like that had been previously explained in some detail and forms the basis of the present invention is in all other respects an electrically operated lock of a modern construction in which there is further provided an electrically powered auxiliary opening drive which is switched on or activated in order to lift the lock catch component out of its full closure or preliminary or partial closure engagement for the purpose of opening the door. Even here, the release triggering criterion may be and often is a pull on either the internal or the external release or opening handle or grip when the vehicular lock is unlocked. As a result of this action, the electrical auxiliary opening drive is set in operation and thereafter acts on a lock latch component in such a manner that the latter is lifted out of its engaged position with the lock catch component. Detailed solutions addressing this aspect have been known, in principle, for quite some time, as evidenced for instance by the German patent documents DE-A-29 49 319 and DE-A-32 42 527, but also from the German patent document DE-C-43 21 586 and the European patent document EP-A-0 589 158.
In the electric motor operated drives for such purely electrically powered motor vehicle door locks, the displacement times of and the maximum force that can be applied (disengagement force) to the lock catch component are given or predetermined by the dimensioning or selection of the available motor torque, step-down ratio of the step-down transmission and the geometry or configurations of the lock latch and lock latch components. In normal operation, when the vehicle is intact and the on-board electrical network of the vehicle delivers its full design voltage to the electrically powered parts of the lock, it is possible, by using a single-stage step-down transmission, to open the vehicle door lock within a predetermined time interval of 150 milliseconds so long as the force acting on the lock catch component that is to be overcome does not exceed approximately 1,000 Newtons. However, under certain, relatively infrequently encountered circumstances or conditions (icing, accident or the like), the forces acting on and/or to be overcome before being able to release the lock catch component may be substantially higher than that, so that then the lock catch component cannot be lifted out of its engaged state without resorting to extraordinary measures. Yet, it is desirable that, even under these conditions, the electric motor powered motor vehicle door lock be able to overcome comparable forces with approximately the same response characteristic as encountered in a purely mechanically operated vehicle door lock while still achieving acceptably low displacement times. This should be achievable even if the voltage supplied by the on-board electrical network and/or by a reserve battery is significantly reduced from its nominal or design level. However, one has to bear in mind that, in such emergency or extraordinary situations, forces of up to approximately 7,500 Newtons may be acting on the lock catch component. It can then be easily imagined how high the magnitude of the frictional forces to be overcome during the disengagement of the lock catch component must be.
Even the problem discussed above has already been recognized and addressed by a variety of technical measures. A first one of such measures includes the use of a two-stage transmission for the auxiliary opening drive, which operates in normal operational mode only in one rotational sense, which can also be referred to as the normal turning direction, and which then acts on the lock latch component with a relatively low step-down transmission ratio; yet, in the emergency or extraordinary situation mentioned above, the two-stage transmission is being operated in the opposite rotational sense, which may thus also be referred to as the emergency turning direction, and then acts on the lock latch component with a considerably higher step-down transmission ratio. In this construction, when a higher than normal resistance force is encountered at the lock catch component, the occurrence of this situation is detected by an appropriate sensor located on the electric motor drive, and causes the latter to operate in the opposite rotational sense, that is in the aforementioned emergency turning direction. While operating in this reverse direction, the step-down transmission exhibits a significantly increased step-down transmission ratio, so that the lock latch component is moved towards and into its opening or disengaged position, albeit with an increased displacement time period, with a force that is sufficient for this emergency situation.
In the technical concept solution that had been mentioned before (that disclosed in the German patent document DE-A-197 10 531), which may be used in conjunction with the vehicle lock with the auxiliary closing and opening drives that constitutes the basis of the present invention (i.e. that according to the German patent document DE-A-197 14 992), the electronic control equipment must recognize when the need arises for the reversal of the rotational sense of the electric motor drive. For instance, this may be the case when, after a predetermined time interval has elapsed since the issuance of the opening command, the lock latch component has still not been lifted or disengaged, when the occurrence of too high a displacement force is sensed (e.g. the driving motor draws a higher amount of electric current than acceptable, the speed of rotation of the driving motor decreases significantly, or the like), when the occurrence of an accident has been detected by a crash sensor as is well known, when the output power of the electric driving motor is too low, for instance as the result of a decrease in the voltage delivered by the on-board electrical network or of special environmental conditions or effects, or when a switchover has taken place from the regular electric power supply equipment to an emergency electric power supply equipment.
An alternative approach to the solution of the problem of the elevated level of the opening forces to be applied in the event of an emergency resides in the provision of a spring force storage device which is loaded during the return of the auxiliary opening drive from the open position to the closed position and which enhances the advancement and lifting movement of the lock latch component by the application of the thus accumulated spring force during the movement of the auxiliary opening drive from the closed position to the open position (see for instance the German patent document DE-C-197 25 416).
Finally, it is known from the documents mentioned before (DE-C-4321 586, DE-A-32 42 527, EP-B-0 496 736) to use the auxiliary closing drive also, when being operated in the reverse direction, as an auxiliary opening drive. Inasmuch as the auxiliary closing drive is ordinarily considerably more powerful than the auxiliary opening drive, the resort to the use of this expedient makes it possible, with the proper design of the step-down transmission inclusive of appropriate selection of its step-down ratio, to obtain a level of the lifting forces acting on the lock latch component that is required for the emergency situation at hand. However, complex and hence rather expensive gear or link transmission structures have to be utilized in the prior solutions mentioned above in order to accomplish the various force application directions.
Accordingly, it is a general object of the present invention to avoid the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide an electrically powered lock for motor vehicle doors or the like that does not possess the drawbacks of the known locks of this type.
Still another object of the present invention is to devise a lock of the type here under consideration which is capable of being opened even in emergency situations resulting in the existence of forces in the lock that the regular opening drive is unable to overcome.
It is yet another object of the present invention to design the above lock in such a manner as to take into account most if not all of the emergency situations that may arise.
A concomitant object of the present invention is so to construct the lock of the above type as to be relatively simple in construction, inexpensive to manufacture, easy to use, and yet reliable in operation.
In keeping with the above objects and others which will become apparent hereafter, one feature of the present invention resides in a lock for doors of motor vehicles or the like which includes a housing; a lock catch component mounted on the housing for movement between an initial open position and a fully closed position through an intermediate position and including a preliminary and a final abutment; a lock latch component mounted on the housing for displacement between an arresting position and a releasing position in which it engages and disengages one of the preliminary and final abutment of the lock catch component to hold the latter in and release the same for movement out of the intermediate and fully closed position, respectively; means for causing the lock latch component to disengage the one of the abutments of the lock catch component to release the latter for the movement thereof toward the initial open position, including an electrically powered auxiliary opening drive; means for moving the lock catch component from the intermediate into the fully closed position thereof, including an electrically powered auxiliary closing drive which includes a step-down transmission and means for connecting the step-down transmission with the lock latch component, including a driving- element and a coupling interposed between the driving element and the lock latch component; and means for enabling the auxiliary closing drive to act on the lock latch component as well when necessary for it to act on the latter to displace the same out of engagement with the one abutment of the lock catch component. According to the present invention, there is further provided means for controlling the operation of the drives, including means for determining the occurrence of an emergency situation involving the action on the lock catch component of excessive forces making it necessary to employ the auxiliary closing drive to accomplish the disengagement, and means for operating the auxiliary closing drive in such a manner after a demand for opening the lock has been issued in the emergency situation that the auxiliary closing drive acts to disengage the lock latch component from the lock catch component.
A particular advantage of the lock structure as described so far is that it is based on the recognition of the fact that ordinarily the auxiliary closing drive is designed and dimensioned for sustaining and exerting forces exceeding those for which the auxiliary opening drive is designed. This is then utilized in accordance with the present invention by employing the auxiliary closing drive as a sort of an xe2x80x9cemergency opening drivexe2x80x9d. Yet, the auxiliary closing drive is used in its additional capacity as an auxiliary opening drive only in what is referred to herein as an emergency situation, that is any situation in which there is a need to apply to the lock latch component forces, torques or the like that exceed those that the regular auxiliary drive is capable of delivering at that moment for whatever reason. Of course, one has to take into account a significantly increased opening time under these circumstances. This second utility for the auxiliary closing drive despite the presence of the regular auxiliary opening drive is a peculiar feature of the teaching of the present invention.
According to another aspect of the present invention, the lock further includes means for disengaging the coupling at the commencement of the operation of the operating means at the latest. In this respect, it is particularly advantageous when the coupling includes a coupling element that is mechanically movable out of its position in which it engages its counterpart in response to a predetermined action of the auxiliary opening drive, and when the control means includes means for causing the auxiliary opening drive, after the determining means has determined the occurrence of the emergency situation, to perform the predetermined action to initially achieve the disengagement of the coupling.
The auxiliary closing drive may be operatable in a non-reversing manner; in that case, the operating means for the auxiliary closing drive is operative for leaving the latter after the completion of the movement of the lock catch component into the fully closed position thereof in an opening-readiness position that is situated considerably ahead of an initial position assumed by the auxiliary closing drive prior to the commencement of such operation thereof. However, the auxiliary closing drive may also be operatable in a reversing manner, in which case the operating means for the auxiliary closing drive is operative for returning the latter after the completion of the movement of the lock catch component into the fully closed position thereof into an initial position assumed by the auxiliary closing drive prior to the commencement of such operation thereof, and means for causing the auxiliary closing drive to move in a reverse direction in the event of the occurrence to cause the disengagement of the lock latch component from the lock catch component.
It is also advantageous when the driving element of the auxiliary closing drive is a force-transmitting lever acting on the lock catch component and including an entraining portion positioned to act on the lock latch component in the even of the occurrence. Another feature of the present invention may be found in a lock for doors of motor vehicles or the like which again includes a housing; a lock catch component mounted on the housing for movement between an initial open position and a fully closed position through an intermediate position and including a preliminary and a final abutment; a lock latch component mounted on the housing for displacement between an arresting position and a releasing position in which it engages and disengages one of the preliminary and final abutment of the lock catch component to hold the latter in and release the same for movement out of the intermediate and fully closed position, respectively; means for causing the lock latch component to disengage the one of the abutments of the lock catch component to release the latter for the movement thereof toward the initial open position, including an electrically powered auxiliary opening drive; and means for moving the lock catch component from the intermediate into the fully closed position thereof, including an electrically powered auxiliary closing drive which includes a step-down transmission and means for connecting the step-down transmission with the lock latch component, including a driving element and a coupling interposed between the driving element and the lock latch component. In this context, the present invention further includes means for controlling the operation of the drives, including means for determining the occurrence of an emergency situation involving the action on the lock catch component of excessive forces making it necessary to employ the auxiliary closing drive to aid in accomplishing the disengagement, means for operating the auxiliary closing drive in such a manner after a demand for opening the lock has been issued in the emergency situation as to move the lock catch component further in the closing direction to thereby relieve the forces acting between the lock latch component and the lock catch component, and means for subsequently operating the auxiliary opening drive to disengage the lock latch component from the lock catch component.
The construction of this lock is based, in accordance with the present invention, on the recognition of the fact that the excessive disengagement of lifting forces encountered in the emergency situations are caused, in most if not all instances, by the friction between the end surface of the lock latch component and the corresponding (abutment) surface of the lock latch component. This friction is reduced in accordance with the invention in that the auxiliary closing drive is energized at first in an emergency situation to act in the initial closing direction to move the lock latch and lock catch components slightly apart or at least to reduce the forces acting between them. Once this is accomplished, it is the regular auxiliary opening drive that actually accomplishes the opening process in the same manner as in a non-emergency situation, since the adverse effect of the excess forces on its operation has been overcome by the action of the auxiliary closing drive. However, especially in this alternative, it is important to assure, by appropriately designing the control means, that the auxiliary opening drive is caused to hold the lock latch component in its disengaged position until the lock catch component has reached its open position.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.